Solar energy collector apparatus

Abstract

The disclosure relates to a three piece solar energy bulb type collector device comprising a hollow glass body shaped with a parabolic interior surface that is coated with specular finish of a metal, e.g. silver, and includes an apex aperture and integral hollow yoke. A glass test-tube like element is exteriorly coated with a wave length selective coating having more than 0.8 absorption above 2.5 microns wave length and less than 0.1 emission at 2.5 microns or less wave lengths. The coated glass tube is the absorber and has an intermediate rib and flared open end which are fused with glass at the aperture area and open end of the yoke. The absorber is coaxially located with the focal axis of the parabolic surface. A cover plate is sealed over the large end of the parabolic body enclosing the interior mirror surface area in a chamber which is placed under vacuum (evacuated). Working media, which may be either gas or liquid, is circulated from a manifold through the absorber tube to remove solar energy as heat, and is returned to the manifold. The solar energy laden media is available for heating, cooling or power generating applications.

What is claimed is: 
     
       1. A solar collector apparatus comprising an integral endless glass wall defining a parabolic surface disposed about a central focal axis, an aperture at one end of said wall centered on said axis at the apex of said parabolic surface, the opposite end of said wall defining an enlarged open end, a continuous reflective coating layer over the parabolic surface of said wall for reflecting solar radiation striking said surface to said focal axis,   a hollow, tubular glass member having a closed end and an opposite open end, said member being inserted through said aperture and coaxial with said focal axis such that the open end thereof is disposed adjacent the apex aperture,   fusion connecting means sealingly attaching said hollow tubular glass member integrally with said parabolic glass wall at the apex aperture region thereof,   said tubular glass member including an energy absorbing surface thereon extending over substantially the entire surface area thereof disposed along the focal axis of said parabolic wall,   a transparent glass cover member for covering the open end of said parabolic wall opposite the aperture thereof, and   means for sealingly connecting the glass cover plate over said parabolic glass wall closing the parabolic chamber defined thereby, said chamber being evacuated to at least a partial vacuum.   
     
     
       2. The solar collector apparatus of claim 1, wherein the fusion connecting means for attaching the tubular glass member in said apex aperture comprises a glass-to-glass seal between said tubular member and the glass wall. 
     
     
       3. The solar collector apparatus of claim 1, wherein the said reflective coating on the parabolic surface of said wall comprises a specular reflective surface. 
     
     
       4. The solar collector apparatus of claim 1, wherein the energy absorbing surface on said tubular glass member is disposed at least over the exterior surface of said tubular member disposed along said focal axis and within said parabolic surface, whereby said energy absorbing surface is in the chamber that is evacuated to a vacuum condition. 
     
     
       5. The solar collector apparatus of claim 4, wherein said energy absorbing surface comprises a wave length selective coating on the exterior surface of said tubular member. 
     
     
       6. The solar collector apparatus of claim 5, in which said wave length selective coating is characterized by having the properties of more than 0.8 absorption in wave lengths above 2.5 microns and less than 0.1 emission in wave lengths of 2.5 microns and less. 
     
     
       7. A solar collector apparatus comprising an endless glass wall forming a parabolic surface disposed about a central focal axis and having a rim edge at one end thereof defining an enlarged opening and an annular hollow yoke portion at the other end thereof extending outwardly beyond the apex of said parabolic surface that is concentric on said focal axis and open at its opposite axial ends, the yoke providing an aperture in said parabolic surface, a hollow, tubular glass member having a closed end and an opposite open end, said member being inserted through said aperture and disposed in said yoke and coaxial with said focal axis such that the open end thereof extends beyond said apex aperture,   a fusion means for annularly sealingly connecting the hollow tubular glass member and said glass wall,   a reflective coating over the parabolic surface of said wall for reflecting solar radiation striking said surface to said focal axis,   said tubular glass member including an energy absorbing surface thereon extending over substantially the entire surface area thereof disposed along the focal axis within said parabolic wall,   a transparent glass cover member for covering the open end of said parabolic wall opposite the aperture thereof,   means for sealingly connecting the glass cover plate about the rim edge of said parabolic glass wall closing the parabolic chamber defined thereby, said chamber being evacuated to at least a partial vacuum,   a manifold providing a conduit for flow of working fluid, said manifold including means for sealingly connecting said open end of the hollow tubular glass member to the manifold whereby the hollow tubular member is in communication with said conduit, and   means for introducing working fluid from the manifold conduit internally of the tubular member in heat exchange relation therewith and returning the solar energy laden working fluid to said manifold conduit.   
     
     
       8. The solar collector apparatus of claim 7, wherein the means for introducing working fluid from the manifold conduit into the hollow tubular member and return to the manifold conduit comprises a partition member in said conduit and extending into said tubular member, said partition member blocking flow in said conduit and bisecting the interior of said tubular member, whereby flow of working fluid in the manifold on one side of said partition member is diverted for counterflow along the interior wall of the tubular member and return to the manifold on the other side of the partition member. 
     
     
       9. The solar collector apparatus of claim 8, in which the working fluid is a gas. 
     
     
       10. The solar collector apparatus of claim 7, wherein the means for introducing working fluid from the manifold into said tubular member comprises a longitudinal wall means dividing the manifold conduit into two substantially parallel passageways, an aperture in the manifold connected to one of the passageways and receiving the yoke portion of the glass wall member, a delivery tube axially disposed through said manifold aperture and connected to the other of the passageways, said delivery tube extending internally of said tubular member and spaced from the closed end thereof, whereby flow of working fluid in the other of the passageways of the manifold is conducted through said delivery tube into and through the interior of said tubular member in a counterflow pattern and into the one passageway of the manifold, the working fluid being heated by the flow in the tubular member. 
     
     
       11. The solar collector apparatus of claim 10, in which the working fluid is a liquid. 
     
     
       12. The solar collector apparatus of claim 7, including a layer of thermal insulating material encasing the manifold. 
     
     
       13. The solar collector apparatus of claim 12, in which the thermal insulating material on the manifold comprises a layer of foamed polyurethane. 
     
     
       14. The solar collector apparatus of claim 7, wherein the means sealingly connecting the yoke to the manifold comprises an annular aperture in the manifold wall connected to the conduit thereof, said yoke portion being inserted into the aperture, and annular gasket means encircling said yoke compressed in the aperture between the yoke and the manifold wall. 
     
     
       15. The solar collector apparatus of claim 7, in which the reflective coating is characterized by being a specular coating of a metal and the energy absorbing surface of the tubular glass member comprises a wave length selective coating on the exterior surface of said tubular glass member, said selective coating having properties of absorption of more than 0.8 in wave lengths above 2.5 microns and emission of less than 0.1 in wave lengths of 2.5 microns and less. 
     
     
       16. The solar collector apparatus of claim 7, in which the means annularly sealingly connecting the hollow tubular glass member and said glass wall comprises a glass-to-glass fusion connection of said glass tubular member and said glass wall adjacent said aperture end of the yoke portion thereof, thereby sealing the apex aperture end of the parabolic chamber. 
     
     
       17. The solar collector apparatus of claim 16, wherein the tubular member includes an annularly outwardly flared portion thereon at an intermediate axial location to provide an outer cross dimension thereof at least equal to the cross dimension of the apex aperture, the glass of said flared portion being fused with the glass of said glass wall around the apex aperture thereof. 
     
     
       18. The solar collector apparatus of claim 7, in which a portion of the glass of said hollow tubular member is fused with the glass of the interior of the yoke, thereby providing a glass-to-glass seal between said tubular member and the said glass wall in the yoke portion thereof.